Lift-trucks comprise various parts that are movable axially relative each other or with respect to the chassis of the truck. For example, an extendable mast of the lift-truck may comprise two or more mast segments which are slidable arranged in each other so that the segments may be moved apart and extended telescopically. The lift-truck may further comprise a movable carrier which supports components of the lift-truck. For example the lift-truck may comprise a carrier for supporting load engagement means such as forks or clamping means. The carrier is arranged to be moved along a mast segment of the lifting mast of the lift-truck. A lift-truck comprising load engagement means in the form of a lifting fork is typically denominated a forklift-truck. In so-called reach lift-trucks, the mast of the lift-truck is attached to a carrier, i.e. a mast carriage, which is movable along an element of the lift-truck, for example along the support legs of the lift-truck or along a U-beam in the support legs.
Typically, guide-rolls are provided to ensure a smooth axial movement of one part relative the other part. For example, guide rolls may be arranged between a fixed mast segment and a movable mast segment of an extendable mast. The hub of a guide-roll is thereby attached to one of the mast segments whereby the roll itself engages one of the opposing sidewalls of a track which extends along the other mast segment. A carrier for load engagement means may be provided with guide rolls which run in tracks on the inner mast segment of the lift-truck.
The guide-roll stabilizes the relative movement of the parts in the intended axial direction of movement since the surface of the guide roll is in contact with one of the opposing sidewalls of the track. However, to ensure a completely smooth relative movement between the parts it may often be necessary to prevent movement between the movable parts in directions which are non-parallel to the intended axial direction of movement. For this purpose, the guide roll may comprise a sliding block which protrudes from the hub of the guide roll and is arranged to slide along the bottom of the track. Examples of guide-rolls with sliding blocks for lift-trucks are disclosed in the documents WO2006024522, U.S. Pat. Nos. 4,234,057, 4,914,712, SE460116 and U.S. Pat. No. 4,375,247.
However, occasionally the tracks in which the guide-rolls run are not sufficiently straight, for example the bottom of the flanged track may be uneven. It is also possible that external forces may displace one of the parts in relation to the other. This may cause the sliding block of a conventional guide-roll to be pressed with an uneven pressure onto the bottom of the track. This is turn may result in uneven and sometimes excessive wear of the sliding block.
Thus, it is an object of the present disclosure to provide an improved guide-roll arrangement for guiding movement of second mast segment relative a first mast segment of a lift-truck, whereby said guide-roll arrangement solves or at least mitigates at least one of the problems of the prior-art. In particular, it is an object of the present disclosure to provide a guide-roll arrangement which has long service life. It is also an object of the present disclosure to provide a lift-truck comprising an improved guide-roll arrangement.